U.S. Pat. No. 5,273,564 issued Dec. 28, 1993 to the assignee of this application discloses a one-piece framework for holding the filter media of an air filter. The framework includes a pair of end walls integrally connected to a pair of frame members by a living hinge so that they may be pivotally moved between an assembled and unassembled position. A pair of sidewalls are integrally connected to the frame members by a living hinge only at their outermost ends so that they too may be pivotally moved between their assembled and unassembled position. The sidewalls and the end walls are provided with a closure arrangement in the form of a projection and a tab-like latch pivoting independently in hinge fashion and having an opening, the walls of which frictionally surround the projection in a snap-fit and lock the sidewalls to the end walls in an assembled state.
In the prior art housing described above, the latch is integrally attached to the sidewalls and the end walls of the housing framework by a living hinge of the type employed between the frame members and the sidewalls and the end walls. For the living hinge to function properly, it must be flexed directly from the mold while still warm. If not properly flexed, the hinge becomes brittle and is prone to breakage. The assembler must also allow ample time to properly flex each of the existing living hinges which contributes to worker fatigue and associated motion problems. In addition, manually snapping the individual latch assemblies on the framework requires considerable and continuous hand pressure which may lead to further worker fatigue and decreased production.
Therefore, it is desirable to provide an upgraded latch assembly for an air filter housing which offers advantages over the prior art including ease of production for the molder, ease of assembly, and better resistance to fracture. Such latch assembly should be simple and reliable in operation and allow quick, convenient access for replacing the filter media in the housing.